http://www.bimmer.info/forum/forumdisplay.php?f=10

OK,

The only advice I received here (alt.autos.bmw) was to consult the
bimmer.info forums, which I did.  And I did get some good advice from a
number of folks that had done this job before.  I am posting my thanks
and appreciation there, but also wanted to post a follow-up here as
well, as a means to capture the answers for posterity.

First off, it seems that some flavors of the E34 (later years only?
8-cylinders only?, not sure...) got an additional cross member.  This is
a bent, round section of frame that goes across from one thrust arm
bushing mount to the other.  It appears to do little other than possibly
shore-up any frame flex due to force from the thrust arms?  The cross
member is item #1 in this illustration:

http://www.realoem.com/bmw/showparts.do?model=HE63&mospid=47410&btnr=31_0250&hg=
31&fg=05

The large bolt for this cross member (13), also goes through the plate
that the stabilizer bar mounts to (12).  Dropping the cross member is
the key to getting access to the nut on the end of the thrust arm
bushing bolt (11).

In my case, I went out and bought a new craftsman 6 point, 18mm 1/2"
drive socket because the 18mm socket I had already was a 12 point.  I
had given it one try already and realized I would need to use more force
than I was comfortable putting on the 12 pointer.  Good thing I chose
craftsman because, after slathering the bolts with PBblaster, the left
side cracked loose pretty easily.  The right side cracked too, but it
was the socket that cracked this time.  Ooops...  Back to Sears
Essentials (used to be K-mart) for a free replacement.

With my replacement socket in place, I heated the crap out of the bolt
and was finally able to get it to budge.  Whew!!  Thought I was finally
going to have to buy that air compressor and impact gun that I've always
wanted.  ;-)

I did not actually have to remove the cross-member entirely.  I just
loosened the large bolt about 1/2" which allowed me to get a box-end
wrench over the nut and crank on the bolt head from the other end.
After the new thrust arms and control arms were installed, I left this
crossmemeber loose until after the I had tightened the bushing bolts to
spec with the wheels back on and the suspension loaded.  A good set of
ramps are worth their weight in gold for that task.

How did it come out?  Great.  It really tightened up the front end and I
don't get any braking wobble anymore.  The steering has even tightened
up.  What I assumed was accumulated slop in the steering gearbox has
been eliminated.

By the way, you could not tell that there was anything wrong with the
Thrust Arm bushings just by looking at them.  They looked fine.  The
wobble symptom was the only clue.  But the balljoints on the control
arms were bad (visibly and audibly) and the braking vibes at 50-60 mph
told me it was time for them to go too.